I am still experimenting with how to improve my flow in the tank. I have two spraybars across the back of a 180 litre tank at water level with a good jet to the front of the tank. One Eheim 2217 has its input from the back right of the tank and its sprayar enters from the left and flows to centre. the other 2217 is the reverse (inlet back left, spraybar right to centre). I use a koralia 1 to push the CO2 around the tank and this faces forward at the waterline on the far left of the tank (where the CO2 diffuser is). Here is the thing: orientated like this the two spraybars have flow directed to the front of the tank but each with jets which direct toward the centre. Surely at the centre of the tank there is some interference between them. Do others orientate things this way or is it better to have both filter inlets in the back right of the tank, and both spraybars entering from the left, with a longer hose on one so that the spraybar only begins after the first stops (i.e still across the length of the tank but both flowing the same direction).